Heat exchange apparatus



Oct. 15, 1957 F. E. CARROLL, JR., ET AL HEAT EXCHANGE APPARATUS Filed OCT.. 22, 1954 @TLV T, ,r TTORNE United States Patent O HEAT EXCHANGE APPARATUS Frank E. Carroll, Jr., Raymond S. De Groote, and Robert E. Hall, Dayton, Ohio, assignors to United Aircraft Products, Inc., Dayton, Ohio, a corporation of Ghia Application October 22, 1954, Serial No. 463,934 6 Claims. (Cl. 257-2) This invention relates to heat exchange apparatus, and although not so limited has especial reference to liquid to liquid exchangers as used in aircraft engine installation wherein owing fuel and circulating lubricant are brought into heat exchange relation for cooling of the lubricant or heating of the fuel or both.

An object of the invention is to present a generally new heat exchange device of the class described which is materially smaller and more compact than like devices of the prior art and which performs at an eiiciency at least equal to that of such prior devices.

Another object of the invention is to obviate the need for flowing fuel through the heat exchange area in an amount in excess of that required for heat rejection, it being contemplated that excess fuel ows shall be bypassed about the heat exchange area.

A further object of the invention is to limit the fuel pressure drop across the heat exchanger to a predetermined maximum.

Still another object of the invention is to control ow of the lubricant through the heat exchanger in accordance with a changing condition of the fuel, it being proposed in the illustrative embodiment of the invention continuously to sense the temperature of the fuel after it leaves the heat exchanger and to exert as a result of such sensing process a modulating control over lubricant or oil ilow in a manner to restrict the fuel out temperature to a maximum.

A still further object of the invention'is to present a generally new core structure for heat exchangers of the kind described embodying a unitary by-pass and means for obtaining a cross iow of the oil through the heat exchanger.

in the drawings,

Fig. l is a view substantially in cross section through a heat exchange device in accordance with the illustrative embodiment of the invention; and

Fig. 2 is a view in cross section taken substantially along the line 2--2 of Fig. l.

In the illustrative form of the invention, a shell is defined for the heat exchanger by inner and outer tubular shell elements 10 and 11. At their opposite ends the tubular shell elements 10 and 11 respectively engage opposite sides of a flange 12 on a tube sheet 13 and a ilange i4 on a tube sheet 15. V'The shell elements thereby are held spaced apart and define therebetween a chamber 16. Mounted on the tube sheet 13, in effect to form a continuation of the shell, is an adapter 17 open at its outer end to admit fuel and mounting a plate 18 facilitating a plumbing connection in the fuel supplyrlines. Mounted on the tube sheet is an adapter 19 the outer end of which is closed by a plate 21. An opening 22 in the plate 21 is substantially axially aligned with the tube sheets 13 and 15 and is closed 4by a removable cap 23. Relatively thin walled heat exchange tubes 24 extend between the tube sheets 1,3.and 15 and have their opposite ends opening therethrough. Thus, fuel admitted to adapter 17 iills what is in effect an inlet chamber 25 therein and 2,809,810' Patented Oct. 15,219.57

may flow through the tubes 24 and be discharged into what may be termed an outlet chamber 26 in adapter 19. Also extending between the tube sheets 13 and 15 is a central conduit 27 of large capacity relatively to individual tubes 24 and serving as a by-pass between the inlet and outlet chambers 25 and 26. A pressure relief valve 28 has a sliding mounting in the cap 23 and is urged by a compression spring 29 to a position closing the outlet end of the conduit 27. The construction and arrangement of parts is such that fuel in inlet chamber 25 will tend normally to flow through the tubes 24 but upon attainment of a predetermined maximum pressure drop in the fuel between the inlet chamber 25 and the outlet chamber 26, valve 28 will open permitting the excess fuel to by-pass the tubes 24 and maintaining such fuel pressure drop at the selected maximum value.

The tubes 24 are arranged in or occupy an annular space between the conduit 27 and the shell elements 10-`-l1. The ends of the tubes, as well as the ends of the conduit 27, are installed in the tube sheets 13 and 15 in a fluid tight manner, as will be understood, as for example by brazing. The tubes 22, moreover, are spaced apart from one another and from the shell wall and from the conduit 27 in a manner to define ow spaces therearound for the oil. The latter is admitted to the shell by way of a lateral opening 31 therein and is discharged by way of an opening 32 in the inner shell element 10 leading to the passage 16 and a lateral outlet opening 33 in the outer shell element 11.

Inlet 31 and outlet opening 32 are spaced apart substantially the full length of the heat exchanger shell so that the admitted oil may travel nearly the full length of the tubes 24.

The inlet 31 is structurally made up of aligned openings 34 and 35 in elements 10 and 11. The opening 35 is somewhat larger than the opening 34 and receives a ferrule 36, the inner edge of opening 34 being bent in ward upon the ferrule.

Within the annular space occupied by the tubes 24 are installed baffles 37 and 38 in separate series. The baffles 37 and 38 are ring shaped to surround the conduit 27 and the `baffles 37 may be described as relatively large. Thus, the latter baffles have outer peripheral edges contacting the wall of inner shell element 10 and have inner peripheral edges spaced from the conduit 27, each in a manner to define an annular passage 39 between the inner edge of the baffle and the surface of the conduit 27. The

smaller bafes 38 (of which there is only one in the illustrated embodiment of the invention) has its inner peripheral edge contacting the conduit 27 and its outer peripheral edge spaced from the wall of inner shell element 10 in a manner to deline an annular passage 41 between the outer edge of the baflle and the surface of shell element 1t). The baffles 37 and 38 are installed in an alternating relation whereby to induce in the flowing oil a cross iiow action as indicated by the dotted line arrows in Fig. 1.

The flow paths for the fuel are indicated by full line arrows in Fig. l and it will be seen that the fuel is permitted to escape from the outlet chamber 26 by way of a lateral opening 42 in the adapter 19.

Suitably mounted on the shell of the heat exchanger, as by welding, is a pad 43 having openings aligned with and in effect forming xcontinuations of shell openings 31, 33 and 42. Bolted or otherwise removably installed on the pad 43 is a valve hou-sing 44 having bottom openings 45, 46 and 47 respectively aligned with and communicating with the shell openings 31, 33 and 42. The housing 44 further is formed with chambers 48, 49, 51 and 52. Chamber 48 represents the oil inlet chamber, having an opening 53 for connection with an oil supply line leading from the engine. The chamber 49 represents the oil outlet chamber, having an opening 54 adapted to be connected in an oil return line. Chamber 51 communicates with shell opening 31 by way of housing opening 45, and further communicates with inlet chamber 48 by way of ran opening ,55 in the Wall of the valve housing. Another opening 56 communicates inlet chamber 48 directly with outlet chamber 49, and the latter communicates through opening 46 with shell outlet opening 33. The hou-sing chamber 52 communicates through opening 47 with the shell opening 42 through which fuel which has already passed through the heat exchanger escapes. A longitudinal opening 57 provides Va route out of the chamber 52 for the fuel, and there may be installed in suchV opening, as indicated, a fitting S facilitating attachment in a continuing fuel flowing line.

The openings 55 and 5 6 in the housing 44 are aligned with one another and with an end closure member 59 in the housing dal. A rod 61 extends longitudinally through the openings 55 and 5.6 and .has vone .end slidably mounted in .a .bearing .62 in the closure member 59. The opening 56 is formed with a valve seat 63 facing into the outlet chamber 49. A poppet type valve 64 is slidably mounted on Athe rod v61 to engage the seat 63 ,and is urged to an engaged position by `an assembly .of compression springs 65 .and .66 reacting against .the closure member 59. The rod 61 is threaded and adjustment nuts 67 are mounted thereon to provide a stop for `the valve .64 independently of the seat 63. Also mounted on the rod 61, as lby being pinned thereto, is aY sleeve valve .63 having a sliding bearing inthe opening 55 and formed with a radial opening .69 through which inlet chamber 48 may communicate with the chamber 51. The rod 61 is engaged by a plunger 71' which extends from a thermostat 72 located in the chamber 52. Through the plunger 71, the thermostat assembly is 'mounted in a wall 73 separating the chambers 51 and 52 and in which there may further be installed a seal 74 acting more .positively to preclude the mingling of oil in chamber 51 with fuel in chamber 52. The outer case only of the thermostat '72 is illustrated, but it will be understood that the thermostat construction in View is that of a known kind wherein a thermally sensitive material within the case 72 expands when heated and projects the plunger 71 outward or in a right hand direction as seen in Fig. l. Cooling of the thermal material permits contraction thereof, which is effected through action of the springs 65 and 66. A threaded sleeve 75 extends from the case of the thermostat 72 through the wall 73 vand has a nut 7,6 mounted thereon as a reactant Vmember so that expansion of the thermal material in the thermostat necessarily is resolved into an outward or right hand extending movement of the plunger 71. Such extension of the thermostat plunger is effective Vaxally to move the rod 61 with the result that opening 69 in valve 63 is moved fully Within opening 55 and thereby is closed While at the same time valve 6d is moved off of its seat 63 to open communication between chambers 48 and 49 directly through opening 56. The valve 64, it will be understood, also is pressure. responsive in operation independently of the thermostat. Thus,.in response to a predetermined pressure differential between the chambers 48 and 49 the valve 64 will open and allow a by-passing flow of the oil directly to the heat exchanger outlet without passing through an area of heat exchange relation to the fuel. Such an action might oecur,.for example, upon an engine start under low temperature conditions causing a high oil viscosity.

In the operation of the heat exchange apparatus, fuel under pressure is supplied inlet chamber 25 of the heat exchanger shell. Initially, t-he fuel finds valve 28 at the end of by-pass conduit 27 closed and so tends exclusively toow through the tubes 24. The fuel is discharged from the tubes 24 into outlet chamber 26 and escapes therefrom by way of openings 42 and 47 into the thermostat chamber 52 ofthe valve housing 44. -Within chamber 52, therfuelwashes the thermostat 72 and passes out of the heat exchange apparatus by way of the opening 57. As the pressure difference between the inlet chamber 25 and outlet chamber 26 rises to a predetermined Value, the spring 29 yields permitting valve 28 to move to an open position relatively to the conduit 27. The result, as will be understood, is to by-pass through the conduit 27 all of the fuel supplied inlet chamber 25 which is in excess of the heat rejection requirements o fthe apparatus. In normal operation, therefore, the valve 28` functions to maintain and limit the pressure difference across the heat exchange means to a predetermined maximum.

Oil under pressure is admitted to the heat exchange apparatus by way of opening 53 in the valve housing 44, communicating with the inlet chamber 48. The valve 68 normally stands in the position illustrated in Fig. l, or substantially in such position, so that the oil admitted to chamber 48 may flow therethrough and through opening 55 to chamber 51 of the valve housing kand thence by way of openings 45 4and 31 tothe interior of the shell element 10. Within the shell, `the oil follows the alternately converging andexpanding path indicated lin dotted line arrow representation and as defined by the baffles 37 and 38. Thus, owing longitudinally along and partly in cross flow relation to the tubes 24, `the oil travels substantially the full length of the shell and then passes through opening 32 into the chamber 16 and Athence out of the Vshell by way of opening `33 to outlet chamber 49 of the valve housing 44. From the chamber 49 the oil returns by way of opening 5.4 to :the oil circulating system. The Afuel and the oil are thus irl heat ,exchange relation through the tubes 24. The koil is hot relatively to the fuel, and rejects heat to ,the fuel resulting in a corresponding cooling of the oil and warming of the fuel. The latter action results in an 4expansion of the thermal ,material in the thermostat '-72 tending to close valve 6K8 and to open valve 64. Some of the oil admitted to the heat exchange yapparatus may `in vthis manner kbe by-passed lthrough the opening 5,6 ,without reaching Ithe heat exchangearea, witha consequent modulating effectrholcling the fuel out temperature to a predetermined maximum.`

The instant disclosed apparatus is Spcically applicable to aircraft engine installation. AIt will be understood, however, Vthat .the principles involved have amore general utility, lparticularly in regard to environment and the character of the uids brought in heat exchange relation.

Whatis claimedis:

l. Heat vexchange apparatus, including a tubular shell, inlet and outlet chambers at opposite ends vof said shell for `a first uid, said shell having intermediate its ends lateral openings for a second iluid, a tube assembly in said shell through which said first tluidvows from said inlet .to said outletand around which said second fluid passes owing from one toanother of said lateral vopenings, a valve housing mountedon said shell having inlet and outlet chambers in communication with said shell openings and a by-pass therebetween for said .second uid and having an outlet chamber for said rst fluid communicating with the said Outlet chamber at one end of said shell, a valve in said housing controlling said bypass and means in one of said outlet chambers responsive to a changing condition of said first fluid for moving said valve.

2. .Heat exchange apparatus according to claim 1, characterized by a pressure relief valve controlled passage between the inlet and outlet chambers at opposite ends ofthe shell through which a part of said first iluid mayflow in by-passing relation to said tubeassembly.

3. A .heat 4exchangedevice, comprising a shell and a valvehousing inside by side intimately-associated relation, .said shell having lateral openings for inflow and outow of aprst uidand saidhousing having a plurality of chambers, oneofwhich communicates with the inflow opening in .saidshell and another of which communicatesiwith the outow opening-therein; inletJldQlltlet openings in said housing for said rst fluid; vinlet and outlet chambers at opposite ends of said shell for a second uid; an assembly of heat exchange tubes conducting said second uid from said inlet chamber to said outlet chamber, the said rst uid owing through said shell in contact with the exteriors of said tubes; a further chamber in said valve housing communicating with said outlet chamber in said shell and receiving the said second uid therefrom; an outlet opening from said valve housing for said second iluid communicating with said further chamber therein; thermal means in said further chamber influenced by the temperature of said second uid; a valve installed in said housing to control ow of said rst Huid between said inlet opening therein and said one chamber therein; and means for adjusting said valve in response to thermally induced change in said thermal means.

4. A heat exchange device according to claim 3, characterized by still another chamber in said valve housing in joint communication with said inlet opening, said one chamber therein and said other chamber therein, the communication between said still other chamber and said one chamber being controlled by said valve; and a pressure relief valve controlling communication between said still other chamber and said other chamber opening for ow from the former to the latter chambers in response to a predetermined pressure difference therebetween. l

5. A heat exchange device according to claim 3, characterized by a by-pass tube large in relation to individual heat exchange tubes extending longitudinally within said assembly of heat exchange tubes and communicating at its opposite ends with said inlet and outlet chambers; and a valve normally closing the outlet end of said tube and opening to by-pass an excess supply of said second uid,

the by-passed uid mixing with the liuid emerging from said heat exchange tubes prior to contacting said thermal means. y

6. A liquid to liquid heat exchanger wherein a rst liquid which is congealable is brought into heat transfer relation to a second relatively non-congealing liquid acting 4as a coolant, said liquids being supplied under pressure, including means presenting heat transfer Surface, means bringing said liquids into heat transfer relation through said surface, presssure responsive means for bypassing around said heat transfer surface all of said second liquid in excess of that required for a predetermined rate of cooling of said first liquid, and means responding to the temperature of a mixture of the by passing second liquid and of the said second liquid passed in contact with said heat transfer surface for controlling the rate of ow of said rst liquid over said heat transfer surface.

References Cited in the le of this patent UNITED STATES PATENTS 

